1. Field of the Invention
This invention relates to hair spray compositions, and, more particularly, to 80% or less VOC hair spray compositions which have advantageous physical and performance characteristics.
2. Description of the Prior Art
Copolymers of maleic anhydride and methyl vinyl ether, in the form of the C.sub.1 -C.sub.5 alkyl half-ester, e.g. the ethyl half-ester, have been used extensively as the film-forming resin or fixative in hair spray compositions. Generally such ester copolymers have been prepared by polymerization of the monomers benzene or acetone solution in the presence of a free radical polymerization initiator followed by esterification. See Brit. Pats. 863,379; 1,233,468 and 712,220; Ger. Pat. 540,101; and U.S. Pat. Nos. 2,047,398; 4,908,413; 4,939,198; 5,139,034 and 5,223,567.
In general, free radical initiators used in such polymerization processes at elevated temperatures have included alkyl peresters, dialkyl peroxides, perketals, peroxydicarbonates, hydroperoxides, azo compounds and carbon-carbon labile compounds. Copolymerization also has been carried out at relatively low temperatures, e.g. room temperature, using a redox catalyst, such as, a combination of a redox catalyst and ascorbic acid, or, of a peroxydicarbonate and benzoin. It has been possible also to employ the polymerization initiator conjointly with a suitable accelerator, for example, an amine derived from a cyclic or phenyl structure, the amine being used by itself or together with an organic compound of a transition metal. Copolymerization also has been carried out with a mixture of different polymerization initiators having different decomposition temperatures.
The following compounds have been employed as initiators in free radical initiated polymerizations:
acetyl cyclohexanesulfonyl peroxide, PA0 diacetyl peroxydicarbonate, PA0 dicyclohexyl peroxydicarbonate, PA0 di-2-ethylhexyl peroxydicarbonate, PA0 tert-butyl per[oxy]-neodecanoate, PA0 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile); PA0 tert-butylperoxy pivalate, PA0 dioctanoyl peroxide, PA0 dilauroyl peroxide, PA0 2,2'-azobis-(2,4-dimethylvaleronitrile), PA0 tert-butylazo-2-cyanobutane; PA0 dibenzoyl peroxide, PA0 tert-butylper[oxy]-2-ethylhexanoate, PA0 tert-butylper[oxy]maleate, PA0 2,2-azobis(isobutyronitrile); PA0 bis(tert-butylperoxy) cyclohexane, PA0 tert-butylperoxyisopropyl carbonate, PA0 tertbutylper[oxy]acetate; PA0 2,2-bis(tert-butylperoxy)butane, PA0 dicumyl peroxide, PA0 di-tert-amyl peroxide, PA0 di-tert-butyl peroxide, PA0 pinane hydroperoxide, PA0 cumene hydroperoxide, and tert-butyl hydroperoxide. PA0 (a) about 0.5-12% of the ethyl or butyl half-ester copolymer of maleic anhydride and methyl vinyl ether, which is made by copolymerizing the monomers in a solvent at a predetermined temperature, in the presence of a selected amount of a polymerization initiator whose decomposition fragments in the solution are soluble in a 55% VOC hydroalcoholic composition, followed by esterification, preferably in the absence of an esterification catalyst, and wherein the copolymer solution is crystal clear, has a low weight average molecular weight of about 30,000 to about 120,000, preferably 50,000 to 100,000, and most preferably 60,000 to 80,000, a narrow polydispersity or molecular weight distribution (MWD) of less than about 2.5, preferably 1.8 to 2.2, and a solution specific viscosity of about 0.25 to 0.39, preferably 0.28 to 0.35, PA0 (b) 0-80% ethanol, PA0 (c) 19-99% water, and PA0 (d) 0-35% propellant.
Ethyl half-esters of copolymers of maleic anhydride and methyl vinyl ether (Gantrez.RTM. ES-225), may be prepared in acetone according to the free radical polymerization process described by Zamora et al., in U.S. Pat. No. 5,223,567, using decanoyl peroxide as the polymerization initiator. Such copolymers are supplied by International Specialty Products, Inc. as a 50% solids solution in ethanol.
Recent governmental legislation, however, has required that hair spray compositions contain only 80% or less volatile organic compounds (VOCs). Accordingly, it has been necessary for formulators of such hair spray products to substitute water for much of the ethanol solvent presently used to dissolve the hair fixative resin. However, an increase in the water content creates some significant problems, including:
A decrease in resin solubility PA1 An increase in solution viscosity PA1 An increase in spray particle size causing a poorer spray pattern PA1 An increase in dry and tack times PA1 A decrease in high humidity curl resistance (hold) PA1 Can corrosion PA1 Solvent-propellant incompatibility. PA1 (i) optionally neutralized in an amount up to about 25 mole %, PA1 1,1'-azobis (1-cyclohexanecarbonitrile); PA1 2,2'-azobis (N,N'-dimethyleneisobutyramidine) dihydrochloride; PA1 2,2'-azobis(2-amidinopropane) dihydrochloride; PA1 2,2'azobis(N,N'-dimethyleneisobutyramidine); PA1 4,4'-azobis(4-cyanopentanoic acid); PA1 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide} ; PA1 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)ethyl]propionamide}; PA1 2,2'-azobis[2-methyl-N-(2-hydroxyethyl) propionamide; and PA1 2,2'-azobis(isobutyramide) dihydrate. PA1 2,2'-azobisobutyronitrile; PA1 2,2'-azobis-(2,4-dimethylvaleronitrile); PA1 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile); PA1 1,1'-azobis-(1-cyclohexanecarbonitrile); and PA1 dimethyl-2,2'-azobis-(isobutyrate).
In aerosol formulations, the presence of water creates two additional problems:
Specifically, in a low VOC formulation, and particularly in a 55% VOC composition, which contains a very high water content, Gantrez.RTM. ES-225 forms only hazy compositions and has a high solution viscosity. These appearance properties are unacceptable commercially because of the cloudy appearance of the product and formation of a precipitate with time. In addition, such high viscosity formulations are difficult to spray adequately into spray patterns of fine particles. Accordingly, Gantrez.RTM. ES-225 has not been considered as a suitable fixative candidate for a 55% VOC hair spray product.
Goertz et al., in U.S. Pat. No. 4,908,413, described the preparation of ethyl half-ester copolymers of maleic anhydride and excess methyl vinyl ether by thermal polymerization of precharged monomers in acetone, followed by a second phase free radical polymerization. Esterification was carried out in ethanol in the presence of an esterification catalyst such as p-toluenesulfonic acid. However, the alcoholic solutions of such copolymers were considered as being only "equivalent in their physical properties and performance characteristics to the corresponding ones obtained by previous processes".
For these and other reasons, there has been an extensive ongoing research and development effort in both the chemical and cosmetic industries to find new polymers, and/or mixtures of polymers, which would provide acceptable 80% and 55% VOC hair spray compositions for the consumer.
Accordingly, it is an object of this invention to provide an 80% or less VOC hair spray composition, particularly a 55% VOC composition, which exhibits excellent performance properties, even at a low fixative solids level, and a clear fixative solution, without precipitate formation, and which has a low solution viscosity, a low copolymer weight average molecular weight and a narrow molecular weight distribution (MWD), and also which forms a spray pattern of small particle size, providing clear, hard fixative films with superior adhesion to the hair of the user, and which provides an effective high humidity curl retention (hold), as well as low tack and dry times, in both pump and aerosol hair spray products.
These and other objects and features of the invention will be made apparent from the following more detailed description of the invention.